Department of Pr imary Industr ies and Water

Annual Waterways Report

Arthur Catchment

Water Assessment Branch

2009

ISSN: 1835-8489

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purpose, without prior written permission being sought from the Department of Primary Industries and Water, on behalf of the Crown in Right of the State of Tasmania.

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and data provided, it is the responsibility of the data user to make their own decisions about the

accuracy, currency, reliability and correctness of information provided.

The Department of Primary Industries and Water, its employees and agents, and the Crown in

the Right of the State of Tasmania do not accept any liability for any damage caused by, or

economic loss arising from, reliance on this information.

DEPARTMENT of

PRIMARY INDUSTRIES and WATER - 2 -

Arthur Catchment

Contents

1. About the

catchment

2. Streamflow and

Water Allocations

3. River Health

1. About the catchment

The Arthur River catchment is located on the north-west coast of Tasmania and is presently used

extensively for forestry production and limited agriculture, but in the past has been subject to

substantial mining activities at Balfour and Mt Bischoff in the upper region of the catchment. The

catchment covers approximately 2,500 km2 and drains westward into the Southern Ocean

through the small coastal township of Arthur River. The total length of the Arthur River is about

180 km, originating near Waratah in the foothills of Mt Bischoff at an altitude of about 800m

above sea level.

The annual average rainfall ranges from about 1000 mm at the catchment outlet to around

2200 mm at Waratah.

DEPARTMENT of

PRIMARY INDUSTRIES and WATER - 3 -

2. Streamflow & Water Allocation

Streamflow

There are no streamflow monitoring stations

maintained in the Arthur River catchment as

part of DPIW’s state-wide monitoring.

Water Allocation

The Arthur catchment had a total of

4,330 ML in licensed allocations for 2008.

The following table shows the breakdown of

the allocations.

Total Allocation

(ML)

Irrigation 1,667

Stock & Domestic 404

Water supply 45

Other 2,214

Of the total licensed water allocation within

this catchment, 3,168 ML is held within

constructed storages and 1,162 ML is taken

directly from rivers and streams.

Water Use Restrictions

There are no water restriction triggers in

existence for the Arthur River catchment.

- 4 -

3. River Health

The Australian River Assessment System (AUSRIVAS) is a

standardised national system for

assessment of river condition that

uses benthic macroinvertebrates.

The AUSRIVAS models predict the

aquatic macroinvertebrate fauna

that would be expected to occur

at a site in the absence of

environmental stress such as

pollution, habitat degradation or

flow regulation. A comparison of

the macroinvertebrates expected

to occur at the test site with those

actually collected (O/E ratio)

provides a site specific measure of

the biological impairment of the

test site. Further details about

AUSRIVAS can be found at:

www.ausrivas.canberra.edu.a

u/ausrivas.

AUSRIVAS assessments are

carried out at two locations in the

Arthur River catchment:

• Pykes Bridge; and

• Tayatea Bridge

Fig: Arthur River at Pykes

Bridge.

Arthur River at Pykes Bridge

This site is in the upper reaches of the Arthur River,

approximately 25 kilometres downstream of the

historic mine at Mt Bischoff at Waratah. The mine

operated between 1878 and 1945 and has created

significant acid mine drainage problems in the Arthur River and its upper tributaries.

The Arthur River at this site is 21 to 24 metres

wide and consists of fast flowing riffles and runs

flowing over a boulder/cobble substrate. Riparian

vegetation is predominantly native and in an

undisturbed state with the exception of the now

disused picnic/recreational area immediately

adjacent to this site. The surrounding land lies

within the Murchison forest district and is utilised

for timber production.

Although the site is considered to be in good

condition as measured by the combined season

models (A Band or greater), examination of the

single season riffle outputs shows that there is

considerable variation in O/E which range from

0.78 (Band B) to 1.21 (Band X). Similarly single

season edgewater assessments vary considerable

in O/E with a range of 0.59 (Band B) to 1.20 (Band

X). The noted variation is most likely associated

with rain and higher flows during which there is a

rapid influx of highly acidic water into the river

which has impacted on the macroinvertebrate

fauna.

NameNameNameName SeasonSeasonSeasonSeason O/E TaxaO/E TaxaO/E TaxaO/E Taxa BandBandBandBand O/E TaxaO/E TaxaO/E TaxaO/E Taxa BandBandBandBand

RiffleRiffleRiffleRiffle EdgewaterEdgewaterEdgewaterEdgewater

Arthur River at Spr03/ Au04 0.92 A 0.94 A

Pykes Bridge Spr04/ Au05 0.9 A NS

Spr05/ Au06 0.93 A 1 A

Spr06/ Au07 0.97 A 1.21 X

Spr07/ Au08 1.01 A NS

Au08/ Spr08 1.03 A NS

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Spr03/ Au04 Spr04/ Au05 Spr05/ Au06 Spr06/ Au07 Spr07/ Au08 Au08/ Spr08

O/E Taxa

Season

Riffle

Edgewater

Fig: Combined season AUSRIVAS O/E Taxa scores

for the Arthur River at Pykes Bridge.

- 5 -

Arthur River at Tayatea Bridge

This site is approximately 67

kilometres downstream of the site

at Pykes Bridge and 14 kilometres

upstream of the confluence of the

Rapid and Arthur Rivers. This site is located within the production

zone of the Circular Head forest

district and the surrounding land is

used for timber production.

Riparian vegetation is

predominantly native and in an

undisturbed state with the

exception of a small picnic/

recreational area immediately

adjacent to this site. The river is

between 25 to 50 metres wide and

consists of fast flowing riffles and

runs over predominantly

cobble/pebble substrate. There

are also sections having a high

proportion of bedrock.

Water quality at the site was

generally good with all physico-

chemical water quality variables

within expected ranges. pH values

were lower in spring compared to

the following autumn. This was

due to the influx of acidic water

into the river in the upper

catchment following rain.

Fig: Arthur River at Tayatea

Bridge.

Biological assessments indicate that the site is in good

condition with macroinvertebrate communities

containing taxa typical of fast flowing rivers.

Assessments using the combined season models

indicate that the riffle habitat varies between equivalent to reference (Band A) and significantly

impaired (Band B) whilst the edgewater habitat

remains as equivalent to reference (Band A) condition.

Single season AUSRIVAS models consistently returned

high O/E values with averages of 0.98 and 1.08 for the

riffle and edgewater habitats respectively.

NameNameNameName SeasonSeasonSeasonSeason O/E TaxaO/E TaxaO/E TaxaO/E Taxa BandBandBandBand O/E TaxaO/E TaxaO/E TaxaO/E Taxa BandBandBandBand

RiffleRiffleRiffleRiffle EdgewaterEdgewaterEdgewaterEdgewater

Arthur River Spr94/ Au95 0.87 A 1 A

at Tayatea Bridge Spr95/ Au96 0.78 B 1.03 A

Spr03/ Au04 0.89 A 1.14 A

Spr04/ Au05 1.01 A 1.14 A

Spr05/ Au06 0.85 B 1.06 A

Spr06/ Au07 0.8 B 1 A

Spr07/ Au08 0.95 A NS

Au08/ Spr08 0.94 A NS

0

0.2

0.4

0.6

0.8

1

1.2

Spr94/ Au95

Spr95/ Au96

Spr03/ Au04

Spr04/ Au05

Spr05/ Au06

Spr06/ Au07

Spr07/ Au08

Au08/ Spr08

O/E Taxa

Season

Rif f le

Edgewater

Fig: Combined season AUSRIVAS O/E Taxa scores for

the Arthur River at Tayatea Bridge.